In recent years, more and more electronic devices such as tablet personal computers and portable digital assistants include touchscreens to improve operability and usability. A user can enter information on a position on a display surface of the liquid crystal panel by touching the display surface of the liquid crystal panel with a finger or a stylus. According to this configuration, the user can perform intuitive operation, that is, the user can perform operation with direct feeling as if he or she directly touches an image displayed on the liquid crystal panel. Such a touchscreen is disclosed in Patent Document 1.
Patent Document 1 discloses a touch panel controller including a driving section, a differential amplifier, and correction means. The driving section is for driving drive lines DL1 to DL4 on the basis of a code sequence to output a first linear sum of capacitance values of electrostatic capacitors C31 to C34 between the respective drive lines DL1 to LD4 and a sense line SL3 and to output a second linear sum of capacitance values of electrostatic capacitors C41 to C44 between the respective drive lines DL1 to DL4 and a sense line SL4. The differential amplifier is for amplifying a difference between the first linear sum and the second linear sum. The correction means is for correcting a line dependency between the capacitance values of the electrostatic capacitors C31 to C34 and the capacitance values of the electrostatic capacitors C41 to C44.